GeoHot released blackra1n. blackra1n is a 30 second ALL device firmware 3.1.2 jailbreak. There is even supports for iPod Touch 3G jailbreak. For now there is only a version for Windows, but the Mac version should be released soon (UPDATE: Mac version is ready)
Download blackra1n utility
PS: Blackra1n doesn’t hacktivate the device.